1. Field of the Invention.
This invention relates in general to a coupling network or means for an electronic circuit.
2. Description of the Prior Art.
Noise in electronic systems is largely unwanted. The following quote is from pages 9 and 10 of the book Noise in Electronics by Courtney Hall (1973):
Small random voltages and currents exist in electrical components and circuits. These fluctuations are referred to as noise because they generally serve no purpose and can interfere with the measurement or detection of useful signals. Such noise sources are inherent in most electronic components and cannot be eliminated. Noise has little importance in electronic systems when signals are very much larger or stronger than the noise. If, however, the signal is very small or weak, the noise may be sufficient to render the signal undetectable. Thus, noise becomes very important when dealing with very low level signals. Noise is the limiting factor in determining the maximum sensitivity of an electronic system.
Various coupling networks have been developed for conveying electronic signals from one stage of an electronic circuit to another stage. For example, a weak audio signal may require several stages of amplification by way of a cascade amplifier or the like to produce the necessary gain in signal strength. The signal is transferred from the output of one stage to the input of the next stage by way of a coupling network or means. A typical coupling means is shown in FIG. 3 of the drawings connecting two triodes and comprising in general a capacitor C electrically coupled between the plate circuit of the first triode T' and the grid circuit of the second triode T". A resistor R is normally used relative to the capacitor for use as the load for one stage across which the output voltage is developed. Such coupling means do not disclose or suggest the present invention. Such prior art amplifier coupling networks are thought by persons skilled in the art to amplify first the inherent noise of the components and then the signals on a logarithmic scale thereby causing a logarithmic gain in the noise.